Manufacture of fiber gasket material



Patented Mar. 11, 1952 MANUFACTURE OF FIBER GASKET MATERIAL John W. Baymiller, Manheim Township, Lancaster County, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania 'No Drawing. Application September 20, 1948, Serial No. 50,240

9 Claims.

This invention relates to the manufacture of fiber gasket material. More particularly, the invention relates to a method of saturating fibrou sheet material as well as to a new saturant for fibrous sheet material.

Fiber gasket material has been manufactured for many years by a process which includes passing a fibrous sheet through a "bath containing binder material in suspension or in solution to saturate the sheet, insolubilizing the binder, and drying the resulting saturated sheet to obtain the desired gasket material.

Various organic fibers have been employed in the manufacture of sheets which are saturated in accordance with conventional saturating methods. Typical of the organic fibers which have been used are kraft fibers, cotton linters, leather fibers, and the like. As binders, numerous materials have been employed. For example, resinous binders; latex binders, both natural .rubber and synthetic rubber latices; as well as various drying oils have found use in the manufacture of fiber gasket material. However, the most common binders for use in the manufacture of oil resistant fiber gasket material are plasticized glue compounds, and it is to these types that my invention applies particularly. These compounds include glue and a suitable plasticizer .such as the polyhydric alcohols, for example ethylene glycol, glycerine, and the like. Glueglycerine saturants tanned with formaldehyde are widely used in saturating fibrous sheet material for the manufacture of gaskets.

While the conventional glue-glyoerine aturants have been employed with success, the saturating methods utilizing such saturants have resulted in variability in the products obtained. This variability is due to the tendency for glue to hydrolyze and degrade under the usual saturating practice and to the variability and uncertainty of the formaldehyde tanning reaction even under carefully controlled conditions. This is particularly noticeable in the manufacture of saturated fibrous sheets when low loads are applied. In many instances, it is desirable to utilize a low saturant load such as 50% to 75% based on the weight of the fiber to obtain lower costs and special properties and, in such cases, there is considerable variability in the properties of the saturated sheet obtained.

Attempts have been made over the years to improve the saturating methods discussed hereinabove by the addition of various ingredients to the aturants employed. However, many of the additives have been somewhat expensive and, in

addition, a number of them have resulted in less desirable products because of the fact that undesirable side reactions take place during the saturating process. For instance, certain additives have, under the conditions of saturation, formed resinous condensation products. thereby resulting in undesirable properties in the saturated sheet.

It is an object of my invention to provide an improved saturant for fibrous sheet material which may be utilized in conventional saturating equipment.

A further object of my invention is the provision of an improved saturant possessing high stability under the conditions obtaining in the saturating process.

Still another object of my invention is the provision of a plasticized glue type saturant which may be employed in a process operated at substantially lower temperatures than have heretofore been used.

Still another object of my invention is the provision of a saturated fibrous sheet having unusually high tensile strength.

These and other objects of my invention will become apparent to those skilled in the art upon becoming familiar with the following description.

In accordance with my invention, I provide a plasticized glue saturant containing triethanolamine and resorcinol. By plasticized glue saturant, I mean to include saturants having a glue base and containing a plasticizer therefor such as the polyhydric alcohols conventionally employed. Typical plasticized glue saturants are glue-glycerine, glue-glycol, and the like. By including in the plasticized glue saturant a combination of resorcinol and triethanolamine, I have obtained a saturant which may be utilized in conventional equipment operating, however, at substantially lower temperatures. While I do not intend to be limited to any'particular theory expressed herein, it is believed that the resorcinol serves to combine with and peptize the glue component in the presence of triethanolamine, thereby enabling the operation of the aturating process at lower temperature because of the lower viscosity of the saturant. I am unable to employ resorcinol alone because it reacts with formaldehyde to produce an insoluble resin which precipitates under the conditions obtaining in the saturating process resulting in a saturated sheet of somewhat undesirable characteristics. The presence of triethanolamine alone imparts n 9 outtanding advantages, but with the combination of triethanolamine and resorcinol, the outstanding results mentioned herein are obtained.

While the proportions of the ingredients in my new plasticized glue type saturant may be varied depending, among other things; upon the particular paper or other fibrous sheet being saturated, the temperature of the bath, and the like, generally speaking, I have obtained particularly advantageous results with a saturant which contains about 0.025 to 0.3 part of resorcinolfor each part of glue present therein. I find no particular advantages to be gained by employing less than 0.025 part of resorcinol. However, when more than 0.3 part of resorcinol per part of glue is employed, a certain amount of insoluble resorcinol-formaldehyde resin is produced and the final product may be somewhat brittle for use as a gasket material. In order to obtain advantageous results, I also find that not less than 0.2 parts of triethanolamine should be employed in the saturant based upon one part by weight of the glue content. With less than this amount present, there is a tendency for the resorcinol to react too rapidly to form undesirable by-products in the saturant. As far as I can determine, there is no upper limit to the amount of, triethanolamine which may be employed. In fact, if desired, the triethanolamine, in addition to its effect on the resorcinol-glueformaldehyde reaction, may be employed for all or part of the glue plasticizer constituent. In other Words, triethanolamine may be used in lieu of glycerine or other glue plasticizers. However, it is, generally speaking, desirable to include glycerine or equivalent polyhydric alcohols as the glue plasticizer of my invention.

A typical saturant made in accordance with my invention is illustrated by the following specific example:

In one embodiment of the process of my invention, a fibrous sheet such as kraft paper is passed through a bath containing a saturant such as that set forth in the example at a temperature which is advantageously between about 70 F. to 90 F. Particularly advantageous results have been obtained by saturating at a temperature between about 70 F. to 80 F. The passage through the bath is controlled by any means known to the art so that saturation of the sheet is substantially complete. At the end of the bath, the excess saturant is removed from the sheet by passing through squeeze rolls or other equivalent devices. After saturation, the binder is insolubilized which is generally carried out by dipping the sheet into a formaldehyde solution to tan the glue. After removal from the tan bath, the sheet may be immediately dried at a temperature such as 150 F. to 180 F. It is advantageousv however, to mull the sheet, or allow time for the tanning reaction, for a comparatively short period of time such as five to ten minutes. It is to be noted that the process of my invention, because of the type of saturant, may be carried out at approximately room tem perature in contrast to temperatures of 120 F. and higher which are generally used in saturatmg processes including plasticized glue type saturants. In addition, the mulling time is reduced 4 to practically zero when compared with mulling times normally employed with plasticized glue processes, which times are in the order of sixteen hours.

An additional advantage to be gained by the practice of my invention is that the saturated sheet as it is withdrawn from the saturating bath may be tanned by means of comparatively small amounts of formaldehyde. About 3% to 8% by weight of formaldehyde based on the glue content of the sheet may be employed with excellent results. In fact, tanning ma be obtained with about 3% to 5% by weight of formaldehyde on the glue. This is a reduction in formaldehyde content over that generally employed in conventional processes wherein it is common to use 8% to 10% formaldehyde based on the glue.

Not only has the saturant of my invention enabled substantial improvements in the process of making fibrous sheet material, but the final products possess unusual characteristics. Fiber gasket materials obtained by conventional glueglycerine saturating methods generally have tensile strengths in the order of about 2,000 to 3,000 pounds per square inch. I have found that, utilizing the same saturating paper with my process and saturant. tensile strengths of about 3,000 to 5,000 pounds per square inch are obtained. In addition, the saturated paper possesses high crush resistance which is important where high bolt or flange pressures are involved in the assembly of the gasket.

While I have described my invention with reference to certain particular examples and with reference to certain particular embodiments, it is to be understood that the invention is not limited thereby. Therefore, changes, omissions, substitutions, and/or additions may be made without departing from the spirit of the invention as defined in the appended claims which are intended to be limited only as required by the prior art.

I claim:

1. A saturant for fibrou sheet material comprising plasticized glue, resorcinol, and triethanolamine said resorcinol being present in an amount equal to 0.025 to 0.3 part by weight for each part of glue, said triethanolamine being present in an amount equal to at least 0.2 part by weight for each part of glue.

2. A saturant for fibrous sheet material comprising glue, glycerine, triethanolamine, and re sorcinol said resorcinol being present in an amount equal to 0.025 to 0.3 part by weight for each part of glue, said triethanolamine being present in an amount equal to at least 0.2 part by weight for each part of glue.

3. A saturant for fibrous sheet material comprising 1 part by weight of glue, 0.025 to 0.3 part by weight of resorcinol, and at least 0.2 part by weight of triethanolamine.

4. A saturant for fibrous sheet material comprising the following ingredients in the following proportions by weight:

Glue 1.0 Resorcinol 0.1 Glycerine 3.5 Triethanolamine 0.2 Water 8.0

5. A process of saturating fibrous sheet material comprising passing a sheet of fibrous material through a bath containing a dispersion of one part by weight of glue, 0.025 to 0.3 part by weight of resorcinol, and at least 0.2 part by weight of triethanolamme while maintaining a temperature of between about 70 F. and 90 F., insolubilizing the saturant with formaldehyde, and drying the resulting sheet.

6. Amethod of making saturated fibrous sheet material for use in the manufacture of gaskets comprising passing a sheet of fibrous material" through a bath containing a saturant including gluef-glycerine, resorcinol, and triethanolamine,;

said resorcinol bein present in an amount equal to 0.025 to 0.3 part by weight for each part of glue: and said triethanolamine being present in anf amount equal to at least 0.2 part by weight for each part of glue, said bath being maintained at} a temperature of between approximately 70 and 90 F., tanning the resulting saturated sheet by means of a formaldehyde solution, mulling the tanned sheet for a short period of time, and dry ing the resulting sheet.

7. A method of making fibrous gasket material which comprises passing a sheet of fibrous mate:- rial through a bath containing a saturant includture between bout 70 F. and 90 F., removing e155- cess saturant, tanning the saturated sheet by passing said sheet through a formaldehyde solvl tion under such conditions that about 3% to formaldehyde based on the weight of the glue combines with said glue in said sheet, mulling said" sheet for a short period of time, and drying the resulting sheet.

8. A saturated fibrous material for use in the manufacture of gaskets characterized by high tensile strength and high crush resistance comprising a fibrous sheet impregnated with a tanned and dried saturant including one part by weight of glue, at least 0.2 part by weight of triethanolamine, and 0.025 to 0.3 part by weight of resorcin01.

9. A fiber gasket material characterized by high tensile strength and crush resistance comprising fibrous material impregnated with a tanned and dried saturant including glue, glycerine, resorcinol, and triethanolamine said resorcinol being present in an amount equal to 0.025 to 0.13 part for each part of glue and said triethanolamine being present in an amount equal to at least 0.2 part for each part of glue.

JOHN W. BAYMILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,921,363 Lefranc Aug. 8, 1933 2,126,305 Babcock Aug. 9, 1938 2,175,773 Hoogstoel Oct. 10, 1939 2,193,818 Kajita et a1 Mar. 19, 1940 2,211,992 Van der Meluen Aug. '20, 1940 2,367,678 Hatch et a1. Jan. 23, 1945 

1. A SATURANT FOR FIBROUS SHEET MATERIAL COMPRISING PLASTICIZED GLUE, RESORCINOL, AND TRIETHANOLAMINE SAID RESORCINOL BEING PRESENT IN AN AMOUNT EQUAL TO 0.025 TO 0.3 PART BY WEIGHT FOR EACH PART OF GLUE, SAID TRIETHANOLAMINE BEING PRESENT IN AN AMOUNT EQUAL TO AT LEAST 0.2 PART BY WEIGHT FOR EACH PART OF GLUE. 